1. Field of the Invention
The present invention relates to an illuminating unit and a projection type image display apparatus using the same and, more particularly, to an illuminating unit having an improved fixing member for mounting light sources and collimators and a projection type image display apparatus using the same.
2. Description of the Related Art
Typically, an illuminating unit includes a light source for outputting a light beam, an illuminating optical module such as a collimator for transferring the light beam output from the light source, and a fixing member for holding the light source and the illuminating optical module. The illuminating unit is usually employed in a projection type image display apparatus which displays images using a non-spontaneous light emitting display device such as a liquid crystal display panel (LCP) or a digital micro-mirror device (DMD). Recently, small, low-power illuminating units have been developed for projection type image display devices, employing small light emitting devices such as light emitting diodes (LEDs) and laser diodes as a light source.
FIG. 1 shows a conventional illuminating unit which uses LEDs. In this illuminating unit, an optical module is used to collimate the light beam output from the LEDs 1, to increase the effective light intensity by condensing the light beams output from the LEDs 1. In addition, because a typical LED emits less light than other light sources such as a metal halide lamp or a mercury lamp, a plurality of LEDs must be used, and these are arranged on a fixing member 3.
The fixing member is required to optimally hold the illumination optical module as well as the light emitting devices, and to effectively serve as a heat sink for the heat generated by the light emitting devices. Unfortunately, there has been no suggestion for satisfying this requirement.